/**
 * @author Rich Tibbett / https://github.com/richtr
 * @author mrdoob / http://mrdoob.com/
 * @author Tony Parisi / http://www.tonyparisi.com/
 * @author Takahiro / https://github.com/takahirox
 * @author Don McCurdy / https://www.donmccurdy.com
 */

THREE.GLTFLoader = ( function () {
    
    function GLTFLoader( manager ) {
        
        this.manager = ( manager !== undefined ) ? manager : THREE.DefaultLoadingManager;
        this.dracoLoader = null;
        
    }
    
    GLTFLoader.prototype = {
        
        constructor: GLTFLoader,
        
        crossOrigin: 'anonymous',
        
        load: function ( url, onLoad, onProgress, onError ) {
            
            var scope = this;
            
            var path = this.path !== undefined ? this.path : THREE.LoaderUtils.extractUrlBase( url );
            
            // Tells the LoadingManager to track an extra item, which resolves after
            // the model is fully loaded. This means the count of items loaded will
            // be incorrect, but ensures manager.onLoad() does not fire early.
            scope.manager.itemStart( url );
            
            var _onError = function ( e ) {
                
                if ( onError ) {
                    
                    onError( e );
                    
                } else {
                    
                    console.error( e );
                    
                }
                
                scope.manager.itemEnd( url );
                scope.manager.itemError( url );
                
            };
            
            var loader = new THREE.FileLoader( scope.manager );
            
            loader.setResponseType( 'arraybuffer' );
            
            loader.load( url, function ( data ) {
                
                try {
                    
                    scope.parse( data, path, function ( gltf ) {
                        
                        onLoad( gltf );
                        
                        scope.manager.itemEnd( url );
                        
                    }, _onError );
                    
                } catch ( e ) {
                    
                    _onError( e );
                    
                }
                
            }, onProgress, _onError );
            
        },
        
        setCrossOrigin: function ( value ) {
            
            this.crossOrigin = value;
            return this;
            
        },
        
        setPath: function ( value ) {
            
            this.path = value;
            return this;
            
        },
        
        setDRACOLoader: function ( dracoLoader ) {
            
            this.dracoLoader = dracoLoader;
            return this;
            
        },
        
        parse: function ( data, path, onLoad, onError ) {
            
            var content;
            var extensions = {};
            
            if ( typeof data === 'string' ) {
                
                content = data;
                
            } else {
                
                var magic = THREE.LoaderUtils.decodeText( new Uint8Array( data, 0, 4 ) );
                
                if ( magic === BINARY_EXTENSION_HEADER_MAGIC ) {
                    
                    try {
                        
                        extensions[ EXTENSIONS.KHR_BINARY_GLTF ] = new GLTFBinaryExtension( data );
                        
                    } catch ( error ) {
                        
                        if ( onError ) onError( error );
                        return;
                        
                    }
                    
                    content = extensions[ EXTENSIONS.KHR_BINARY_GLTF ].content;
                    
                } else {
                    
                    content = THREE.LoaderUtils.decodeText( new Uint8Array( data ) );
                    
                }
                
            }
            
            var json = JSON.parse( content );
            if ( json.asset === undefined || json.asset.version[ 0 ] < 2 ) {
                
                if ( onError ) onError( new Error( 'THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported. Use LegacyGLTFLoader instead.' ) );
                return;
                
            }
            
            if ( json.extensionsUsed ) {
                
                for ( var i = 0; i < json.extensionsUsed.length; ++ i ) {
                    
                    var extensionName = json.extensionsUsed[ i ];
                    var extensionsRequired = json.extensionsRequired || [];
                    
                    switch ( extensionName ) {
                        
                        case EXTENSIONS.KHR_LIGHTS_PUNCTUAL:
                            extensions[ extensionName ] = new GLTFLightsExtension( json );
                            break;
                        
                        case EXTENSIONS.KHR_MATERIALS_UNLIT:
                            extensions[ extensionName ] = new GLTFMaterialsUnlitExtension( json );
                            break;
                        
                        case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
                            extensions[ extensionName ] = new GLTFMaterialsPbrSpecularGlossinessExtension();
                            break;
                        
                        case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
                            extensions[ extensionName ] = new GLTFDracoMeshCompressionExtension( json, this.dracoLoader );
                            break;
                        
                        case EXTENSIONS.MSFT_TEXTURE_DDS:
                            extensions[ EXTENSIONS.MSFT_TEXTURE_DDS ] = new GLTFTextureDDSExtension();
                            break;
                        
                        default:
                            
                            if ( extensionsRequired.indexOf( extensionName ) >= 0 ) {
                                
                                console.warn( 'THREE.GLTFLoader: Unknown extension "' + extensionName + '".' );
                                
                            }
                        
                    }
                    
                }
                
            }
            
            var parser = new GLTFParser( json, extensions, {
                
                path: path || this.path || '',
                crossOrigin: this.crossOrigin,
                manager: this.manager
                
            } );
            
            parser.parse( function ( scene, scenes, cameras, animations, json ) {
                
                var glTF = {
                    scene: scene,
                    scenes: scenes,
                    cameras: cameras,
                    animations: animations,
                    asset: json.asset,
                    parser: parser,
                    userData: {}
                };
                
                addUnknownExtensionsToUserData( extensions, glTF, json );
                onLoad( glTF );
                
            }, onError );
            
        }
        
    };
    
    /* GLTFREGISTRY */
    
    function GLTFRegistry() {
        
        var objects = {};
        
        return	{
            
            get: function ( key ) {
                
                return objects[ key ];
                
            },
            
            add: function ( key, object ) {
                
                objects[ key ] = object;
                
            },
            
            remove: function ( key ) {
                
                delete objects[ key ];
                
            },
            
            removeAll: function () {
                
                objects = {};
                
            }
            
        };
        
    }
    
    /*********************************/
    /********** EXTENSIONS ***********/
    /*********************************/
    
    var EXTENSIONS = {
        KHR_BINARY_GLTF: 'KHR_binary_glTF',
        KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
        KHR_LIGHTS_PUNCTUAL: 'KHR_lights_punctual',
        KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
        KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
        MSFT_TEXTURE_DDS: 'MSFT_texture_dds'
    };
    
    /**
     * DDS Texture Extension
     *
     * Specification:
     * https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
     *
     */
    function GLTFTextureDDSExtension() {
        
        if ( ! THREE.DDSLoader ) {
            
            throw new Error( 'THREE.GLTFLoader: Attempting to load .dds texture without importing THREE.DDSLoader' );
            
        }
        
        this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
        this.ddsLoader = new THREE.DDSLoader();
        
    }
    
    /**
     * Lights Extension
     *
     * Specification: PENDING
     */
    function GLTFLightsExtension( json ) {
        
        this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;
        
        this.lights = [];
        
        var extension = ( json.extensions && json.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ] ) || {};
        var lightDefs = extension.lights || [];
        
        for ( var i = 0; i < lightDefs.length; i ++ ) {
            
            var lightDef = lightDefs[ i ];
            var lightNode;
            
            var color = new THREE.Color( 0xffffff );
            if ( lightDef.color !== undefined ) color.fromArray( lightDef.color );
            
            var range = lightDef.range !== undefined ? lightDef.range : 0;
            
            switch ( lightDef.type ) {
                
                case 'directional':
                    lightNode = new THREE.DirectionalLight( color );
                    lightNode.target.position.set( 0, 0, 1 );
                    lightNode.add( lightNode.target );
                    break;
                
                case 'point':
                    lightNode = new THREE.PointLight( color );
                    lightNode.distance = range;
                    break;
                
                case 'spot':
                    lightNode = new THREE.SpotLight( color );
                    lightNode.distance = range;
                    // Handle spotlight properties.
                    lightDef.spot = lightDef.spot || {};
                    lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
                    lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
                    lightNode.angle = lightDef.spot.outerConeAngle;
                    lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
                    lightNode.target.position.set( 0, 0, 1 );
                    lightNode.add( lightNode.target );
                    break;
                
                default:
                    throw new Error( 'THREE.GLTFLoader: Unexpected light type, "' + lightDef.type + '".' );
                
            }
            
            lightNode.decay = 2;
            
            if ( lightDef.intensity !== undefined ) lightNode.intensity = lightDef.intensity;
            
            lightNode.name = lightDef.name || ( 'light_' + i );
            
            this.lights.push( lightNode );
            
        }
        
    }
    
    /**
     * Unlit Materials Extension (pending)
     *
     * PR: https://github.com/KhronosGroup/glTF/pull/1163
     */
    function GLTFMaterialsUnlitExtension( json ) {
        
        this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;
        
    }
    
    GLTFMaterialsUnlitExtension.prototype.getMaterialType = function ( material ) {
        
        return THREE.MeshBasicMaterial;
        
    };
    
    GLTFMaterialsUnlitExtension.prototype.extendParams = function ( materialParams, material, parser ) {
        
        var pending = [];
        
        materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
        materialParams.opacity = 1.0;
        
        var metallicRoughness = material.pbrMetallicRoughness;
        
        if ( metallicRoughness ) {
            
            if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {
                
                var array = metallicRoughness.baseColorFactor;
                
                materialParams.color.fromArray( array );
                materialParams.opacity = array[ 3 ];
                
            }
            
            if ( metallicRoughness.baseColorTexture !== undefined ) {
                
                pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture.index ) );
                
            }
            
        }
        
        return Promise.all( pending );
        
    };
    
    /* BINARY EXTENSION */
    
    var BINARY_EXTENSION_BUFFER_NAME = 'binary_glTF';
    var BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
    var BINARY_EXTENSION_HEADER_LENGTH = 12;
    var BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4E4F534A, BIN: 0x004E4942 };
    
    function GLTFBinaryExtension( data ) {
        
        this.name = EXTENSIONS.KHR_BINARY_GLTF;
        this.content = null;
        this.body = null;
        
        var headerView = new DataView( data, 0, BINARY_EXTENSION_HEADER_LENGTH );
        
        this.header = {
            magic: THREE.LoaderUtils.decodeText( new Uint8Array( data.slice( 0, 4 ) ) ),
            version: headerView.getUint32( 4, true ),
            length: headerView.getUint32( 8, true )
        };
        
        if ( this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC ) {
            
            throw new Error( 'THREE.GLTFLoader: Unsupported glTF-Binary header.' );
            
        } else if ( this.header.version < 2.0 ) {
            
            throw new Error( 'THREE.GLTFLoader: Legacy binary file detected. Use LegacyGLTFLoader instead.' );
            
        }
        
        var chunkView = new DataView( data, BINARY_EXTENSION_HEADER_LENGTH );
        var chunkIndex = 0;
        
        while ( chunkIndex < chunkView.byteLength ) {
            
            var chunkLength = chunkView.getUint32( chunkIndex, true );
            chunkIndex += 4;
            
            var chunkType = chunkView.getUint32( chunkIndex, true );
            chunkIndex += 4;
            
            if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON ) {
                
                var contentArray = new Uint8Array( data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength );
                this.content = THREE.LoaderUtils.decodeText( contentArray );
                
            } else if ( chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN ) {
                
                var byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
                this.body = data.slice( byteOffset, byteOffset + chunkLength );
                
            }
            
            // Clients must ignore chunks with unknown types.
            
            chunkIndex += chunkLength;
            
        }
        
        if ( this.content === null ) {
            
            throw new Error( 'THREE.GLTFLoader: JSON content not found.' );
            
        }
        
    }
    
    /**
     * DRACO Mesh Compression Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/pull/874
     */
    function GLTFDracoMeshCompressionExtension( json, dracoLoader ) {
        
        if ( ! dracoLoader ) {
            
            throw new Error( 'THREE.GLTFLoader: No DRACOLoader instance provided.' );
            
        }
        
        this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
        this.json = json;
        this.dracoLoader = dracoLoader;
        
    }
    
    GLTFDracoMeshCompressionExtension.prototype.decodePrimitive = function ( primitive, parser ) {
        
        var json = this.json;
        var dracoLoader = this.dracoLoader;
        var bufferViewIndex = primitive.extensions[ this.name ].bufferView;
        var gltfAttributeMap = primitive.extensions[ this.name ].attributes;
        var threeAttributeMap = {};
        var attributeNormalizedMap = {};
        var attributeTypeMap = {};
        
        for ( var attributeName in gltfAttributeMap ) {
            
            if ( ! ( attributeName in ATTRIBUTES ) ) continue;
            
            threeAttributeMap[ ATTRIBUTES[ attributeName ] ] = gltfAttributeMap[ attributeName ];
            
        }
        
        for ( attributeName in primitive.attributes ) {
            
            if ( ATTRIBUTES[ attributeName ] !== undefined && gltfAttributeMap[ attributeName ] !== undefined ) {
                
                var accessorDef = json.accessors[ primitive.attributes[ attributeName ] ];
                var componentType = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];
                
                attributeTypeMap[ ATTRIBUTES[ attributeName ] ] = componentType;
                attributeNormalizedMap[ ATTRIBUTES[ attributeName ] ] = accessorDef.normalized === true;
                
            }
            
        }
        
        return parser.getDependency( 'bufferView', bufferViewIndex ).then( function ( bufferView ) {
            
            return new Promise( function ( resolve ) {
                
                dracoLoader.decodeDracoFile( bufferView, function ( geometry ) {
                    
                    for ( var attributeName in geometry.attributes ) {
                        
                        var attribute = geometry.attributes[ attributeName ];
                        var normalized = attributeNormalizedMap[ attributeName ];
                        
                        if ( normalized !== undefined ) attribute.normalized = normalized;
                        
                    }
                    
                    resolve( geometry );
                    
                }, threeAttributeMap, attributeTypeMap );
                
            } );
            
        } );
        
    };
    
    /**
     * Specular-Glossiness Extension
     *
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
     */
    function GLTFMaterialsPbrSpecularGlossinessExtension() {
        
        return {
            
            name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,
            
            specularGlossinessParams: [
                'color',
                'map',
                'lightMap',
                'lightMapIntensity',
                'aoMap',
                'aoMapIntensity',
                'emissive',
                'emissiveIntensity',
                'emissiveMap',
                'bumpMap',
                'bumpScale',
                'normalMap',
                'displacementMap',
                'displacementScale',
                'displacementBias',
                'specularMap',
                'specular',
                'glossinessMap',
                'glossiness',
                'alphaMap',
                'envMap',
                'envMapIntensity',
                'refractionRatio',
            ],
            
            getMaterialType: function () {
                
                return THREE.ShaderMaterial;
                
            },
            
            extendParams: function ( params, material, parser ) {
                
                var pbrSpecularGlossiness = material.extensions[ this.name ];
                
                var shader = THREE.ShaderLib[ 'standard' ];
                
                var uniforms = THREE.UniformsUtils.clone( shader.uniforms );
                
                var specularMapParsFragmentChunk = [
                    '#ifdef USE_SPECULARMAP',
                    '	uniform sampler2D specularMap;',
                    '#endif'
                ].join( '\n' );
                
                var glossinessMapParsFragmentChunk = [
                    '#ifdef USE_GLOSSINESSMAP',
                    '	uniform sampler2D glossinessMap;',
                    '#endif'
                ].join( '\n' );
                
                var specularMapFragmentChunk = [
                    'vec3 specularFactor = specular;',
                    '#ifdef USE_SPECULARMAP',
                    '	vec4 texelSpecular = texture2D( specularMap, vUv );',
                    '	texelSpecular = sRGBToLinear( texelSpecular );',
                    '	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
                    '	specularFactor *= texelSpecular.rgb;',
                    '#endif'
                ].join( '\n' );
                
                var glossinessMapFragmentChunk = [
                    'float glossinessFactor = glossiness;',
                    '#ifdef USE_GLOSSINESSMAP',
                    '	vec4 texelGlossiness = texture2D( glossinessMap, vUv );',
                    '	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture',
                    '	glossinessFactor *= texelGlossiness.a;',
                    '#endif'
                ].join( '\n' );
                
                var lightPhysicalFragmentChunk = [
                    'PhysicalMaterial material;',
                    'material.diffuseColor = diffuseColor.rgb;',
                    'material.specularRoughness = clamp( 1.0 - glossinessFactor, 0.04, 1.0 );',
                    'material.specularColor = specularFactor.rgb;',
                ].join( '\n' );
                
                var fragmentShader = shader.fragmentShader
                    .replace( 'uniform float roughness;', 'uniform vec3 specular;' )
                    .replace( 'uniform float metalness;', 'uniform float glossiness;' )
                    .replace( '#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk )
                    .replace( '#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk )
                    .replace( '#include <roughnessmap_fragment>', specularMapFragmentChunk )
                    .replace( '#include <metalnessmap_fragment>', glossinessMapFragmentChunk )
                    .replace( '#include <lights_physical_fragment>', lightPhysicalFragmentChunk );
                
                delete uniforms.roughness;
                delete uniforms.metalness;
                delete uniforms.roughnessMap;
                delete uniforms.metalnessMap;
                
                uniforms.specular = { value: new THREE.Color().setHex( 0x111111 ) };
                uniforms.glossiness = { value: 0.5 };
                uniforms.specularMap = { value: null };
                uniforms.glossinessMap = { value: null };
                
                params.vertexShader = shader.vertexShader;
                params.fragmentShader = fragmentShader;
                params.uniforms = uniforms;
                params.defines = { 'STANDARD': '' };
                
                params.color = new THREE.Color( 1.0, 1.0, 1.0 );
                params.opacity = 1.0;
                
                var pending = [];
                
                if ( Array.isArray( pbrSpecularGlossiness.diffuseFactor ) ) {
                    
                    var array = pbrSpecularGlossiness.diffuseFactor;
                    
                    params.color.fromArray( array );
                    params.opacity = array[ 3 ];
                    
                }
                
                if ( pbrSpecularGlossiness.diffuseTexture !== undefined ) {
                    
                    pending.push( parser.assignTexture( params, 'map', pbrSpecularGlossiness.diffuseTexture.index ) );
                    
                }
                
                params.emissive = new THREE.Color( 0.0, 0.0, 0.0 );
                params.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0;
                params.specular = new THREE.Color( 1.0, 1.0, 1.0 );
                
                if ( Array.isArray( pbrSpecularGlossiness.specularFactor ) ) {
                    
                    params.specular.fromArray( pbrSpecularGlossiness.specularFactor );
                    
                }
                
                if ( pbrSpecularGlossiness.specularGlossinessTexture !== undefined ) {
                    
                    var specGlossIndex = pbrSpecularGlossiness.specularGlossinessTexture.index;
                    pending.push( parser.assignTexture( params, 'glossinessMap', specGlossIndex ) );
                    pending.push( parser.assignTexture( params, 'specularMap', specGlossIndex ) );
                    
                }
                
                return Promise.all( pending );
                
            },
            
            createMaterial: function ( params ) {
                
                // setup material properties based on MeshStandardMaterial for Specular-Glossiness
                
                var material = new THREE.ShaderMaterial( {
                    defines: params.defines,
                    vertexShader: params.vertexShader,
                    fragmentShader: params.fragmentShader,
                    uniforms: params.uniforms,
                    fog: true,
                    lights: true,
                    opacity: params.opacity,
                    transparent: params.transparent
                } );
                
                material.isGLTFSpecularGlossinessMaterial = true;
                
                material.color = params.color;
                
                material.map = params.map === undefined ? null : params.map;
                
                material.lightMap = null;
                material.lightMapIntensity = 1.0;
                
                material.aoMap = params.aoMap === undefined ? null : params.aoMap;
                material.aoMapIntensity = 1.0;
                
                material.emissive = params.emissive;
                material.emissiveIntensity = 1.0;
                material.emissiveMap = params.emissiveMap === undefined ? null : params.emissiveMap;
                
                material.bumpMap = params.bumpMap === undefined ? null : params.bumpMap;
                material.bumpScale = 1;
                
                material.normalMap = params.normalMap === undefined ? null : params.normalMap;
                if ( params.normalScale ) material.normalScale = params.normalScale;
                
                material.displacementMap = null;
                material.displacementScale = 1;
                material.displacementBias = 0;
                
                material.specularMap = params.specularMap === undefined ? null : params.specularMap;
                material.specular = params.specular;
                
                material.glossinessMap = params.glossinessMap === undefined ? null : params.glossinessMap;
                material.glossiness = params.glossiness;
                
                material.alphaMap = null;
                
                material.envMap = params.envMap === undefined ? null : params.envMap;
                material.envMapIntensity = 1.0;
                
                material.refractionRatio = 0.98;
                
                material.extensions.derivatives = true;
                
                return material;
                
            },
            
            /**
             * Clones a GLTFSpecularGlossinessMaterial instance. The ShaderMaterial.copy() method can
             * copy only properties it knows about or inherits, and misses many properties that would
             * normally be defined by MeshStandardMaterial.
             *
             * This method allows GLTFSpecularGlossinessMaterials to be cloned in the process of
             * loading a glTF model, but cloning later (e.g. by the user) would require these changes
             * AND also updating `.onBeforeRender` on the parent mesh.
             *
             * @param  {THREE.ShaderMaterial} source
             * @return {THREE.ShaderMaterial}
             */
            cloneMaterial: function ( source ) {
                
                var target = source.clone();
                
                target.isGLTFSpecularGlossinessMaterial = true;
                
                var params = this.specularGlossinessParams;
                
                for ( var i = 0, il = params.length; i < il; i ++ ) {
                    
                    target[ params[ i ] ] = source[ params[ i ] ];
                    
                }
                
                return target;
                
            },
            
            // Here's based on refreshUniformsCommon() and refreshUniformsStandard() in WebGLRenderer.
            refreshUniforms: function ( renderer, scene, camera, geometry, material, group ) {
                
                if ( material.isGLTFSpecularGlossinessMaterial !== true ) {
                    
                    return;
                    
                }
                
                var uniforms = material.uniforms;
                var defines = material.defines;
                
                uniforms.opacity.value = material.opacity;
                
                uniforms.diffuse.value.copy( material.color );
                uniforms.emissive.value.copy( material.emissive ).multiplyScalar( material.emissiveIntensity );
                
                uniforms.map.value = material.map;
                uniforms.specularMap.value = material.specularMap;
                uniforms.alphaMap.value = material.alphaMap;
                
                uniforms.lightMap.value = material.lightMap;
                uniforms.lightMapIntensity.value = material.lightMapIntensity;
                
                uniforms.aoMap.value = material.aoMap;
                uniforms.aoMapIntensity.value = material.aoMapIntensity;
                
                // uv repeat and offset setting priorities
                // 1. color map
                // 2. specular map
                // 3. normal map
                // 4. bump map
                // 5. alpha map
                // 6. emissive map
                
                var uvScaleMap;
                
                if ( material.map ) {
                    
                    uvScaleMap = material.map;
                    
                } else if ( material.specularMap ) {
                    
                    uvScaleMap = material.specularMap;
                    
                } else if ( material.displacementMap ) {
                    
                    uvScaleMap = material.displacementMap;
                    
                } else if ( material.normalMap ) {
                    
                    uvScaleMap = material.normalMap;
                    
                } else if ( material.bumpMap ) {
                    
                    uvScaleMap = material.bumpMap;
                    
                } else if ( material.glossinessMap ) {
                    
                    uvScaleMap = material.glossinessMap;
                    
                } else if ( material.alphaMap ) {
                    
                    uvScaleMap = material.alphaMap;
                    
                } else if ( material.emissiveMap ) {
                    
                    uvScaleMap = material.emissiveMap;
                    
                }
                
                if ( uvScaleMap !== undefined ) {
                    
                    // backwards compatibility
                    if ( uvScaleMap.isWebGLRenderTarget ) {
                        
                        uvScaleMap = uvScaleMap.texture;
                        
                    }
                    
                    if ( uvScaleMap.matrixAutoUpdate === true ) {
                        
                        uvScaleMap.updateMatrix();
                        
                    }
                    
                    uniforms.uvTransform.value.copy( uvScaleMap.matrix );
                    
                }
                
                uniforms.envMap.value = material.envMap;
                uniforms.envMapIntensity.value = material.envMapIntensity;
                uniforms.flipEnvMap.value = ( material.envMap && material.envMap.isCubeTexture ) ? - 1 : 1;
                
                uniforms.refractionRatio.value = material.refractionRatio;
                
                uniforms.specular.value.copy( material.specular );
                uniforms.glossiness.value = material.glossiness;
                
                uniforms.glossinessMap.value = material.glossinessMap;
                
                uniforms.emissiveMap.value = material.emissiveMap;
                uniforms.bumpMap.value = material.bumpMap;
                uniforms.normalMap.value = material.normalMap;
                
                uniforms.displacementMap.value = material.displacementMap;
                uniforms.displacementScale.value = material.displacementScale;
                uniforms.displacementBias.value = material.displacementBias;
                
                if ( uniforms.glossinessMap.value !== null && defines.USE_GLOSSINESSMAP === undefined ) {
                    
                    defines.USE_GLOSSINESSMAP = '';
                    // set USE_ROUGHNESSMAP to enable vUv
                    defines.USE_ROUGHNESSMAP = '';
                    
                }
                
                if ( uniforms.glossinessMap.value === null && defines.USE_GLOSSINESSMAP !== undefined ) {
                    
                    delete defines.USE_GLOSSINESSMAP;
                    delete defines.USE_ROUGHNESSMAP;
                    
                }
                
            }
            
        };
        
    }
    
    /*********************************/
    /********** INTERPOLATION ********/
    /*********************************/
    
    // Spline Interpolation
    // Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
    function GLTFCubicSplineInterpolant( parameterPositions, sampleValues, sampleSize, resultBuffer ) {
        
        THREE.Interpolant.call( this, parameterPositions, sampleValues, sampleSize, resultBuffer );
        
    }
    
    GLTFCubicSplineInterpolant.prototype = Object.create( THREE.Interpolant.prototype );
    GLTFCubicSplineInterpolant.prototype.constructor = GLTFCubicSplineInterpolant;
    
    GLTFCubicSplineInterpolant.prototype.copySampleValue_ = function ( index ) {
        
        // Copies a sample value to the result buffer. See description of glTF
        // CUBICSPLINE values layout in interpolate_() function below.
        
        var result = this.resultBuffer,
            values = this.sampleValues,
            valueSize = this.valueSize,
            offset = index * valueSize * 3 + valueSize;
        
        for ( var i = 0; i !== valueSize; i ++ ) {
            
            result[ i ] = values[ offset + i ];
            
        }
        
        return result;
        
    };
    
    GLTFCubicSplineInterpolant.prototype.beforeStart_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;
    
    GLTFCubicSplineInterpolant.prototype.afterEnd_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;
    
    GLTFCubicSplineInterpolant.prototype.interpolate_ = function ( i1, t0, t, t1 ) {
        
        var result = this.resultBuffer;
        var values = this.sampleValues;
        var stride = this.valueSize;
        
        var stride2 = stride * 2;
        var stride3 = stride * 3;
        
        var td = t1 - t0;
        
        var p = ( t - t0 ) / td;
        var pp = p * p;
        var ppp = pp * p;
        
        var offset1 = i1 * stride3;
        var offset0 = offset1 - stride3;
        
        var s0 = 2 * ppp - 3 * pp + 1;
        var s1 = ppp - 2 * pp + p;
        var s2 = - 2 * ppp + 3 * pp;
        var s3 = ppp - pp;
        
        // Layout of keyframe output values for CUBICSPLINE animations:
        //   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
        for ( var i = 0; i !== stride; i ++ ) {
            
            var p0 = values[ offset0 + i + stride ]; // splineVertex_k
            var m0 = values[ offset0 + i + stride2 ] * td; // outTangent_k * (t_k+1 - t_k)
            var p1 = values[ offset1 + i + stride ]; // splineVertex_k+1
            var m1 = values[ offset1 + i ] * td; // inTangent_k+1 * (t_k+1 - t_k)
            
            result[ i ] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;
            
        }
        
        return result;
        
    };
    
    /*********************************/
    /********** INTERNALS ************/
    /*********************************/
    
    /* CONSTANTS */
    
    var WEBGL_CONSTANTS = {
        FLOAT: 5126,
        //FLOAT_MAT2: 35674,
        FLOAT_MAT3: 35675,
        FLOAT_MAT4: 35676,
        FLOAT_VEC2: 35664,
        FLOAT_VEC3: 35665,
        FLOAT_VEC4: 35666,
        LINEAR: 9729,
        REPEAT: 10497,
        SAMPLER_2D: 35678,
        POINTS: 0,
        LINES: 1,
        LINE_LOOP: 2,
        LINE_STRIP: 3,
        TRIANGLES: 4,
        TRIANGLE_STRIP: 5,
        TRIANGLE_FAN: 6,
        UNSIGNED_BYTE: 5121,
        UNSIGNED_SHORT: 5123
    };
    
    var WEBGL_TYPE = {
        5126: Number,
        //35674: THREE.Matrix2,
        35675: THREE.Matrix3,
        35676: THREE.Matrix4,
        35664: THREE.Vector2,
        35665: THREE.Vector3,
        35666: THREE.Vector4,
        35678: THREE.Texture
    };
    
    var WEBGL_COMPONENT_TYPES = {
        5120: Int8Array,
        5121: Uint8Array,
        5122: Int16Array,
        5123: Uint16Array,
        5125: Uint32Array,
        5126: Float32Array
    };
    
    var WEBGL_FILTERS = {
        9728: THREE.NearestFilter,
        9729: THREE.LinearFilter,
        9984: THREE.NearestMipMapNearestFilter,
        9985: THREE.LinearMipMapNearestFilter,
        9986: THREE.NearestMipMapLinearFilter,
        9987: THREE.LinearMipMapLinearFilter
    };
    
    var WEBGL_WRAPPINGS = {
        33071: THREE.ClampToEdgeWrapping,
        33648: THREE.MirroredRepeatWrapping,
        10497: THREE.RepeatWrapping
    };
    
    var WEBGL_SIDES = {
        1028: THREE.BackSide, // Culling front
        1029: THREE.FrontSide // Culling back
        //1032: THREE.NoSide   // Culling front and back, what to do?
    };
    
    var WEBGL_DEPTH_FUNCS = {
        512: THREE.NeverDepth,
        513: THREE.LessDepth,
        514: THREE.EqualDepth,
        515: THREE.LessEqualDepth,
        516: THREE.GreaterEqualDepth,
        517: THREE.NotEqualDepth,
        518: THREE.GreaterEqualDepth,
        519: THREE.AlwaysDepth
    };
    
    var WEBGL_BLEND_EQUATIONS = {
        32774: THREE.AddEquation,
        32778: THREE.SubtractEquation,
        32779: THREE.ReverseSubtractEquation
    };
    
    var WEBGL_BLEND_FUNCS = {
        0: THREE.ZeroFactor,
        1: THREE.OneFactor,
        768: THREE.SrcColorFactor,
        769: THREE.OneMinusSrcColorFactor,
        770: THREE.SrcAlphaFactor,
        771: THREE.OneMinusSrcAlphaFactor,
        772: THREE.DstAlphaFactor,
        773: THREE.OneMinusDstAlphaFactor,
        774: THREE.DstColorFactor,
        775: THREE.OneMinusDstColorFactor,
        776: THREE.SrcAlphaSaturateFactor
        // The followings are not supported by Three.js yet
        //32769: CONSTANT_COLOR,
        //32770: ONE_MINUS_CONSTANT_COLOR,
        //32771: CONSTANT_ALPHA,
        //32772: ONE_MINUS_CONSTANT_COLOR
    };
    
    var WEBGL_TYPE_SIZES = {
        'SCALAR': 1,
        'VEC2': 2,
        'VEC3': 3,
        'VEC4': 4,
        'MAT2': 4,
        'MAT3': 9,
        'MAT4': 16
    };
    
    var ATTRIBUTES = {
        POSITION: 'position',
        NORMAL: 'normal',
        TEXCOORD_0: 'uv',
        TEXCOORD0: 'uv', // deprecated
        TEXCOORD: 'uv', // deprecated
        TEXCOORD_1: 'uv2',
        COLOR_0: 'color',
        COLOR0: 'color', // deprecated
        COLOR: 'color', // deprecated
        WEIGHTS_0: 'skinWeight',
        WEIGHT: 'skinWeight', // deprecated
        JOINTS_0: 'skinIndex',
        JOINT: 'skinIndex' // deprecated
    };
    
    var PATH_PROPERTIES = {
        scale: 'scale',
        translation: 'position',
        rotation: 'quaternion',
        weights: 'morphTargetInfluences'
    };
    
    var INTERPOLATION = {
        CUBICSPLINE: THREE.InterpolateSmooth, // We use custom interpolation GLTFCubicSplineInterpolation for CUBICSPLINE.
                                              // KeyframeTrack.optimize() can't handle glTF Cubic Spline output values layout,
                                              // using THREE.InterpolateSmooth for KeyframeTrack instantiation to prevent optimization.
                                              // See KeyframeTrack.optimize() for the detail.
        LINEAR: THREE.InterpolateLinear,
        STEP: THREE.InterpolateDiscrete
    };
    
    var STATES_ENABLES = {
        2884: 'CULL_FACE',
        2929: 'DEPTH_TEST',
        3042: 'BLEND',
        3089: 'SCISSOR_TEST',
        32823: 'POLYGON_OFFSET_FILL',
        32926: 'SAMPLE_ALPHA_TO_COVERAGE'
    };
    
    var ALPHA_MODES = {
        OPAQUE: 'OPAQUE',
        MASK: 'MASK',
        BLEND: 'BLEND'
    };
    
    var MIME_TYPE_FORMATS = {
        'image/png': THREE.RGBAFormat,
        'image/jpeg': THREE.RGBFormat
    };
    
    /* UTILITY FUNCTIONS */
    
    function resolveURL( url, path ) {
        
        // Invalid URL
        if ( typeof url !== 'string' || url === '' ) return '';
        
        // Absolute URL http://,https://,//
        if ( /^(https?:)?\/\//i.test( url ) ) return url;
        
        // Data URI
        if ( /^data:.*,.*$/i.test( url ) ) return url;
        
        // Blob URL
        if ( /^blob:.*$/i.test( url ) ) return url;
        
        // Relative URL
        return path + url;
        
    }
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
     */
    function createDefaultMaterial() {
        
        return new THREE.MeshStandardMaterial( {
            color: 0xFFFFFF,
            emissive: 0x000000,
            metalness: 1,
            roughness: 1,
            transparent: false,
            depthTest: true,
            side: THREE.FrontSide
        } );
        
    }
    
    function addUnknownExtensionsToUserData( knownExtensions, object, objectDef ) {
        
        // Add unknown glTF extensions to an object's userData.
        
        for ( var name in objectDef.extensions ) {
            
            if ( knownExtensions[ name ] === undefined ) {
                
                object.userData.gltfExtensions = object.userData.gltfExtensions || {};
                object.userData.gltfExtensions[ name ] = objectDef.extensions[ name ];
                
            }
            
        }
        
    }
    
    /**
     * @param {THREE.Object3D|THREE.Material|THREE.BufferGeometry} object
     * @param {GLTF.definition} def
     */
    function assignExtrasToUserData( object, gltfDef ) {
        
        if ( gltfDef.extras !== undefined ) {
            
            if ( typeof gltfDef.extras === 'object' ) {
                
                object.userData = gltfDef.extras;
                
            } else {
                
                console.warn( 'THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras );
                
            }
            
        }
        
    }
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
     *
     * @param {THREE.BufferGeometry} geometry
     * @param {Array<GLTF.Target>} targets
     * @param {Array<THREE.BufferAttribute>} accessors
     */
    function addMorphTargets( geometry, targets, accessors ) {
        
        var hasMorphPosition = false;
        var hasMorphNormal = false;
        
        for ( var i = 0, il = targets.length; i < il; i ++ ) {
            
            var target = targets[ i ];
            
            if ( target.POSITION !== undefined ) hasMorphPosition = true;
            if ( target.NORMAL !== undefined ) hasMorphNormal = true;
            
            if ( hasMorphPosition && hasMorphNormal ) break;
            
        }
        
        if ( ! hasMorphPosition && ! hasMorphNormal ) return;
        
        var morphPositions = [];
        var morphNormals = [];
        
        for ( var i = 0, il = targets.length; i < il; i ++ ) {
            
            var target = targets[ i ];
            var attributeName = 'morphTarget' + i;
            
            if ( hasMorphPosition ) {
                
                // Three.js morph position is absolute value. The formula is
                //   basePosition
                //     + weight0 * ( morphPosition0 - basePosition )
                //     + weight1 * ( morphPosition1 - basePosition )
                //     ...
                // while the glTF one is relative
                //   basePosition
                //     + weight0 * glTFmorphPosition0
                //     + weight1 * glTFmorphPosition1
                //     ...
                // then we need to convert from relative to absolute here.
                
                if ( target.POSITION !== undefined ) {
                    
                    // Cloning not to pollute original accessor
                    var positionAttribute = cloneBufferAttribute( accessors[ target.POSITION ] );
                    positionAttribute.name = attributeName;
                    
                    var position = geometry.attributes.position;
                    
                    for ( var j = 0, jl = positionAttribute.count; j < jl; j ++ ) {
                        
                        positionAttribute.setXYZ(
                            j,
                            positionAttribute.getX( j ) + position.getX( j ),
                            positionAttribute.getY( j ) + position.getY( j ),
                            positionAttribute.getZ( j ) + position.getZ( j )
                        );
                        
                    }
                    
                } else {
                    
                    positionAttribute = geometry.attributes.position;
                    
                }
                
                morphPositions.push( positionAttribute );
                
            }
            
            if ( hasMorphNormal ) {
                
                // see target.POSITION's comment
                
                var normalAttribute;
                
                if ( target.NORMAL !== undefined ) {
                    
                    var normalAttribute = cloneBufferAttribute( accessors[ target.NORMAL ] );
                    normalAttribute.name = attributeName;
                    
                    var normal = geometry.attributes.normal;
                    
                    for ( var j = 0, jl = normalAttribute.count; j < jl; j ++ ) {
                        
                        normalAttribute.setXYZ(
                            j,
                            normalAttribute.getX( j ) + normal.getX( j ),
                            normalAttribute.getY( j ) + normal.getY( j ),
                            normalAttribute.getZ( j ) + normal.getZ( j )
                        );
                        
                    }
                    
                } else {
                    
                    normalAttribute = geometry.attributes.normal;
                    
                }
                
                morphNormals.push( normalAttribute );
                
            }
            
        }
        
        if ( hasMorphPosition ) geometry.morphAttributes.position = morphPositions;
        if ( hasMorphNormal ) geometry.morphAttributes.normal = morphNormals;
        
    }
    
    /**
     * @param {THREE.Mesh} mesh
     * @param {GLTF.Mesh} meshDef
     */
    function updateMorphTargets( mesh, meshDef ) {
        
        mesh.updateMorphTargets();
        
        if ( meshDef.weights !== undefined ) {
            
            for ( var i = 0, il = meshDef.weights.length; i < il; i ++ ) {
                
                mesh.morphTargetInfluences[ i ] = meshDef.weights[ i ];
                
            }
            
        }
        
        // .extras has user-defined data, so check that .extras.targetNames is an array.
        if ( meshDef.extras && Array.isArray( meshDef.extras.targetNames ) ) {
            
            var targetNames = meshDef.extras.targetNames;
            
            if ( mesh.morphTargetInfluences.length === targetNames.length ) {
                
                mesh.morphTargetDictionary = {};
                
                for ( var i = 0, il = targetNames.length; i < il; i ++ ) {
                    
                    mesh.morphTargetDictionary[ targetNames[ i ] ] = i;
                    
                }
                
            } else {
                
                console.warn( 'THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.' );
                
            }
            
        }
        
    }
    
    function isPrimitiveEqual( a, b ) {
        
        if ( a.indices !== b.indices ) {
            
            return false;
            
        }
        
        return isObjectEqual( a.attributes, b.attributes );
        
    }
    
    function isObjectEqual( a, b ) {
        
        if ( Object.keys( a ).length !== Object.keys( b ).length ) return false;
        
        for ( var key in a ) {
            
            if ( a[ key ] !== b[ key ] ) return false;
            
        }
        
        return true;
        
    }
    
    function isArrayEqual( a, b ) {
        
        if ( a.length !== b.length ) return false;
        
        for ( var i = 0, il = a.length; i < il; i ++ ) {
            
            if ( a[ i ] !== b[ i ] ) return false;
            
        }
        
        return true;
        
    }
    
    function getCachedGeometry( cache, newPrimitive ) {
        
        for ( var i = 0, il = cache.length; i < il; i ++ ) {
            
            var cached = cache[ i ];
            
            if ( isPrimitiveEqual( cached.primitive, newPrimitive ) ) return cached.promise;
            
        }
        
        return null;
        
    }
    
    function getCachedCombinedGeometry( cache, geometries ) {
        
        for ( var i = 0, il = cache.length; i < il; i ++ ) {
            
            var cached = cache[ i ];
            
            if ( isArrayEqual( geometries, cached.baseGeometries ) ) return cached.geometry;
            
        }
        
        return null;
        
    }
    
    function getCachedMultiPassGeometry( cache, geometry, primitives ) {
        
        for ( var i = 0, il = cache.length; i < il; i ++ ) {
            
            var cached = cache[ i ];
            
            if ( geometry === cached.baseGeometry && isArrayEqual( primitives, cached.primitives ) ) return cached.geometry;
            
        }
        
        return null;
        
    }
    
    function cloneBufferAttribute( attribute ) {
        
        if ( attribute.isInterleavedBufferAttribute ) {
            
            var count = attribute.count;
            var itemSize = attribute.itemSize;
            var array = attribute.array.slice( 0, count * itemSize );
            
            for ( var i = 0; i < count; ++ i ) {
                
                array[ i ] = attribute.getX( i );
                if ( itemSize >= 2 ) array[ i + 1 ] = attribute.getY( i );
                if ( itemSize >= 3 ) array[ i + 2 ] = attribute.getZ( i );
                if ( itemSize >= 4 ) array[ i + 3 ] = attribute.getW( i );
                
            }
            
            return new THREE.BufferAttribute( array, itemSize, attribute.normalized );
            
        }
        
        return attribute.clone();
        
    }
    
    /**
     * Checks if we can build a single Mesh with MultiMaterial from multiple primitives.
     * Returns true if all primitives use the same attributes/morphAttributes/mode
     * and also have index. Otherwise returns false.
     *
     * @param {Array<GLTF.Primitive>} primitives
     * @return {Boolean}
     */
    function isMultiPassGeometry( primitives ) {
        
        if ( primitives.length < 2 ) return false;
        
        var primitive0 = primitives[ 0 ];
        var targets0 = primitive0.targets || [];
        
        if ( primitive0.indices === undefined ) return false;
        
        for ( var i = 1, il = primitives.length; i < il; i ++ ) {
            
            var primitive = primitives[ i ];
            
            if ( primitive0.mode !== primitive.mode ) return false;
            if ( primitive.indices === undefined ) return false;
            if ( ! isObjectEqual( primitive0.attributes, primitive.attributes ) ) return false;
            
            var targets = primitive.targets || [];
            
            if ( targets0.length !== targets.length ) return false;
            
            for ( var j = 0, jl = targets0.length; j < jl; j ++ ) {
                
                if ( ! isObjectEqual( targets0[ j ], targets[ j ] ) ) return false;
                
            }
            
        }
        
        return true;
        
    }
    
    /* GLTF PARSER */
    
    function GLTFParser( json, extensions, options ) {
        
        this.json = json || {};
        this.extensions = extensions || {};
        this.options = options || {};
        
        // loader object cache
        this.cache = new GLTFRegistry();
        
        // BufferGeometry caching
        this.primitiveCache = [];
        this.multiplePrimitivesCache = [];
        this.multiPassGeometryCache = [];
        
        this.textureLoader = new THREE.TextureLoader( this.options.manager );
        this.textureLoader.setCrossOrigin( this.options.crossOrigin );
        
        this.fileLoader = new THREE.FileLoader( this.options.manager );
        this.fileLoader.setResponseType( 'arraybuffer' );
        
    }
    
    GLTFParser.prototype.parse = function ( onLoad, onError ) {
        
        var json = this.json;
        
        // Clear the loader cache
        this.cache.removeAll();
        
        // Mark the special nodes/meshes in json for efficient parse
        this.markDefs();
        
        // Fire the callback on complete
        this.getMultiDependencies( [
            
            'scene',
            'animation',
            'camera'
        
        ] ).then( function ( dependencies ) {
            
            var scenes = dependencies.scenes || [];
            var scene = scenes[ json.scene || 0 ];
            var animations = dependencies.animations || [];
            var cameras = dependencies.cameras || [];
            
            onLoad( scene, scenes, cameras, animations, json );
            
        } ).catch( onError );
        
    };
    
    /**
     * Marks the special nodes/meshes in json for efficient parse.
     */
    GLTFParser.prototype.markDefs = function () {
        
        var nodeDefs = this.json.nodes || [];
        var skinDefs = this.json.skins || [];
        var meshDefs = this.json.meshes || [];
        
        var meshReferences = {};
        var meshUses = {};
        
        // Nothing in the node definition indicates whether it is a Bone or an
        // Object3D. Use the skins' joint references to mark bones.
        for ( var skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex ++ ) {
            
            var joints = skinDefs[ skinIndex ].joints;
            
            for ( var i = 0, il = joints.length; i < il; i ++ ) {
                
                nodeDefs[ joints[ i ] ].isBone = true;
                
            }
            
        }
        
        // Meshes can (and should) be reused by multiple nodes in a glTF asset. To
        // avoid having more than one THREE.Mesh with the same name, count
        // references and rename instances below.
        //
        // Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
        for ( var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex ++ ) {
            
            var nodeDef = nodeDefs[ nodeIndex ];
            
            if ( nodeDef.mesh !== undefined ) {
                
                if ( meshReferences[ nodeDef.mesh ] === undefined ) {
                    
                    meshReferences[ nodeDef.mesh ] = meshUses[ nodeDef.mesh ] = 0;
                    
                }
                
                meshReferences[ nodeDef.mesh ] ++;
                
                // Nothing in the mesh definition indicates whether it is
                // a SkinnedMesh or Mesh. Use the node's mesh reference
                // to mark SkinnedMesh if node has skin.
                if ( nodeDef.skin !== undefined ) {
                    
                    meshDefs[ nodeDef.mesh ].isSkinnedMesh = true;
                    
                }
                
            }
            
        }
        
        this.json.meshReferences = meshReferences;
        this.json.meshUses = meshUses;
        
    };
    
    /**
     * Requests the specified dependency asynchronously, with caching.
     * @param {string} type
     * @param {number} index
     * @return {Promise<Object>}
     */
    GLTFParser.prototype.getDependency = function ( type, index ) {
        
        var cacheKey = type + ':' + index;
        var dependency = this.cache.get( cacheKey );
        
        if ( ! dependency ) {
            
            switch ( type ) {
                
                case 'scene':
                    dependency = this.loadScene( index );
                    break;
                
                case 'node':
                    dependency = this.loadNode( index );
                    break;
                
                case 'mesh':
                    dependency = this.loadMesh( index );
                    break;
                
                case 'accessor':
                    dependency = this.loadAccessor( index );
                    break;
                
                case 'bufferView':
                    dependency = this.loadBufferView( index );
                    break;
                
                case 'buffer':
                    dependency = this.loadBuffer( index );
                    break;
                
                case 'material':
                    dependency = this.loadMaterial( index );
                    break;
                
                case 'texture':
                    dependency = this.loadTexture( index );
                    break;
                
                case 'skin':
                    dependency = this.loadSkin( index );
                    break;
                
                case 'animation':
                    dependency = this.loadAnimation( index );
                    break;
                
                case 'camera':
                    dependency = this.loadCamera( index );
                    break;
                
                default:
                    throw new Error( 'Unknown type: ' + type );
                
            }
            
            this.cache.add( cacheKey, dependency );
            
        }
        
        return dependency;
        
    };
    
    /**
     * Requests all dependencies of the specified type asynchronously, with caching.
     * @param {string} type
     * @return {Promise<Array<Object>>}
     */
    GLTFParser.prototype.getDependencies = function ( type ) {
        
        var dependencies = this.cache.get( type );
        
        if ( ! dependencies ) {
            
            var parser = this;
            var defs = this.json[ type + ( type === 'mesh' ? 'es' : 's' ) ] || [];
            
            dependencies = Promise.all( defs.map( function ( def, index ) {
                
                return parser.getDependency( type, index );
                
            } ) );
            
            this.cache.add( type, dependencies );
            
        }
        
        return dependencies;
        
    };
    
    /**
     * Requests all multiple dependencies of the specified types asynchronously, with caching.
     * @param {Array<string>} types
     * @return {Promise<Object<Array<Object>>>}
     */
    GLTFParser.prototype.getMultiDependencies = function ( types ) {
        
        var results = {};
        var pendings = [];
        
        for ( var i = 0, il = types.length; i < il; i ++ ) {
            
            var type = types[ i ];
            var value = this.getDependencies( type );
            
            value = value.then( function ( key, value ) {
                
                results[ key ] = value;
                
            }.bind( this, type + ( type === 'mesh' ? 'es' : 's' ) ) );
            
            pendings.push( value );
            
        }
        
        return Promise.all( pendings ).then( function () {
            
            return results;
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
     * @param {number} bufferIndex
     * @return {Promise<ArrayBuffer>}
     */
    GLTFParser.prototype.loadBuffer = function ( bufferIndex ) {
        
        var bufferDef = this.json.buffers[ bufferIndex ];
        var loader = this.fileLoader;
        
        if ( bufferDef.type && bufferDef.type !== 'arraybuffer' ) {
            
            throw new Error( 'THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.' );
            
        }
        
        // If present, GLB container is required to be the first buffer.
        if ( bufferDef.uri === undefined && bufferIndex === 0 ) {
            
            return Promise.resolve( this.extensions[ EXTENSIONS.KHR_BINARY_GLTF ].body );
            
        }
        
        var options = this.options;
        
        return new Promise( function ( resolve, reject ) {
            
            loader.load( resolveURL( bufferDef.uri, options.path ), resolve, undefined, function () {
                
                reject( new Error( 'THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".' ) );
                
            } );
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
     * @param {number} bufferViewIndex
     * @return {Promise<ArrayBuffer>}
     */
    GLTFParser.prototype.loadBufferView = function ( bufferViewIndex ) {
        
        var bufferViewDef = this.json.bufferViews[ bufferViewIndex ];
        
        return this.getDependency( 'buffer', bufferViewDef.buffer ).then( function ( buffer ) {
            
            var byteLength = bufferViewDef.byteLength || 0;
            var byteOffset = bufferViewDef.byteOffset || 0;
            return buffer.slice( byteOffset, byteOffset + byteLength );
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
     * @param {number} accessorIndex
     * @return {Promise<THREE.BufferAttribute|THREE.InterleavedBufferAttribute>}
     */
    GLTFParser.prototype.loadAccessor = function ( accessorIndex ) {
        
        var parser = this;
        var json = this.json;
        
        var accessorDef = this.json.accessors[ accessorIndex ];
        
        if ( accessorDef.bufferView === undefined && accessorDef.sparse === undefined ) {
            
            // Ignore empty accessors, which may be used to declare runtime
            // information about attributes coming from another source (e.g. Draco
            // compression extension).
            return null;
            
        }
        
        var pendingBufferViews = [];
        
        if ( accessorDef.bufferView !== undefined ) {
            
            pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.bufferView ) );
            
        } else {
            
            pendingBufferViews.push( null );
            
        }
        
        if ( accessorDef.sparse !== undefined ) {
            
            pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.indices.bufferView ) );
            pendingBufferViews.push( this.getDependency( 'bufferView', accessorDef.sparse.values.bufferView ) );
            
        }
        
        return Promise.all( pendingBufferViews ).then( function ( bufferViews ) {
            
            var bufferView = bufferViews[ 0 ];
            
            var itemSize = WEBGL_TYPE_SIZES[ accessorDef.type ];
            var TypedArray = WEBGL_COMPONENT_TYPES[ accessorDef.componentType ];
            
            // For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
            var elementBytes = TypedArray.BYTES_PER_ELEMENT;
            var itemBytes = elementBytes * itemSize;
            var byteOffset = accessorDef.byteOffset || 0;
            var byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[ accessorDef.bufferView ].byteStride : undefined;
            var normalized = accessorDef.normalized === true;
            var array, bufferAttribute;
            
            // The buffer is not interleaved if the stride is the item size in bytes.
            if ( byteStride && byteStride !== itemBytes ) {
                
                var ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType;
                var ib = parser.cache.get( ibCacheKey );
                
                if ( ! ib ) {
                    
                    // Use the full buffer if it's interleaved.
                    array = new TypedArray( bufferView );
                    
                    // Integer parameters to IB/IBA are in array elements, not bytes.
                    ib = new THREE.InterleavedBuffer( array, byteStride / elementBytes );
                    
                    parser.cache.add( ibCacheKey, ib );
                    
                }
                
                bufferAttribute = new THREE.InterleavedBufferAttribute( ib, itemSize, byteOffset / elementBytes, normalized );
                
            } else {
                
                if ( bufferView === null ) {
                    
                    array = new TypedArray( accessorDef.count * itemSize );
                    
                } else {
                    
                    array = new TypedArray( bufferView, byteOffset, accessorDef.count * itemSize );
                    
                }
                
                bufferAttribute = new THREE.BufferAttribute( array, itemSize, normalized );
                
            }
            
            // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
            if ( accessorDef.sparse !== undefined ) {
                
                var itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
                var TypedArrayIndices = WEBGL_COMPONENT_TYPES[ accessorDef.sparse.indices.componentType ];
                
                var byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
                var byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;
                
                var sparseIndices = new TypedArrayIndices( bufferViews[ 1 ], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices );
                var sparseValues = new TypedArray( bufferViews[ 2 ], byteOffsetValues, accessorDef.sparse.count * itemSize );
                
                if ( bufferView !== null ) {
                    
                    // Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
                    bufferAttribute.setArray( bufferAttribute.array.slice() );
                    
                }
                
                for ( var i = 0, il = sparseIndices.length; i < il; i ++ ) {
                    
                    var index = sparseIndices[ i ];
                    
                    bufferAttribute.setX( index, sparseValues[ i * itemSize ] );
                    if ( itemSize >= 2 ) bufferAttribute.setY( index, sparseValues[ i * itemSize + 1 ] );
                    if ( itemSize >= 3 ) bufferAttribute.setZ( index, sparseValues[ i * itemSize + 2 ] );
                    if ( itemSize >= 4 ) bufferAttribute.setW( index, sparseValues[ i * itemSize + 3 ] );
                    if ( itemSize >= 5 ) throw new Error( 'THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute.' );
                    
                }
                
            }
            
            return bufferAttribute;
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
     * @param {number} textureIndex
     * @return {Promise<THREE.Texture>}
     */
    GLTFParser.prototype.loadTexture = function ( textureIndex ) {
        
        var parser = this;
        var json = this.json;
        var options = this.options;
        var textureLoader = this.textureLoader;
        
        var URL = window.URL || window.webkitURL;
        
        var textureDef = json.textures[ textureIndex ];
        
        var textureExtensions = textureDef.extensions || {};
        
        var source;
        
        if ( textureExtensions[ EXTENSIONS.MSFT_TEXTURE_DDS ] ) {
            
            source = json.images[ textureExtensions[ EXTENSIONS.MSFT_TEXTURE_DDS ].source ];
            
        } else {
            
            source = json.images[ textureDef.source ];
            
        }
        
        var sourceURI = source.uri;
        var isObjectURL = false;
        
        if ( source.bufferView !== undefined ) {
            
            // Load binary image data from bufferView, if provided.
            
            sourceURI = parser.getDependency( 'bufferView', source.bufferView ).then( function ( bufferView ) {
                
                isObjectURL = true;
                var blob = new Blob( [ bufferView ], { type: source.mimeType } );
                sourceURI = URL.createObjectURL( blob );
                return sourceURI;
                
            } );
            
        }
        
        return Promise.resolve( sourceURI ).then( function ( sourceURI ) {
            
            // Load Texture resource.
            
            var loader = THREE.Loader.Handlers.get( sourceURI );
            
            if ( ! loader ) {
                
                loader = textureExtensions[ EXTENSIONS.MSFT_TEXTURE_DDS ]
                    ? parser.extensions[ EXTENSIONS.MSFT_TEXTURE_DDS ].ddsLoader
                    : textureLoader;
                
            }
            
            return new Promise( function ( resolve, reject ) {
                
                loader.load( resolveURL( sourceURI, options.path ), resolve, undefined, reject );
                
            } );
            
        } ).then( function ( texture ) {
            
            // Clean up resources and configure Texture.
            
            if ( isObjectURL === true ) {
                
                URL.revokeObjectURL( sourceURI );
                
            }
            
            texture.flipY = false;
            
            if ( textureDef.name !== undefined ) texture.name = textureDef.name;
            
            // Ignore unknown mime types, like DDS files.
            if ( source.mimeType in MIME_TYPE_FORMATS ) {
                
                texture.format = MIME_TYPE_FORMATS[ source.mimeType ];
                
            }
            
            var samplers = json.samplers || {};
            var sampler = samplers[ textureDef.sampler ] || {};
            
            texture.magFilter = WEBGL_FILTERS[ sampler.magFilter ] || THREE.LinearFilter;
            texture.minFilter = WEBGL_FILTERS[ sampler.minFilter ] || THREE.LinearMipMapLinearFilter;
            texture.wrapS = WEBGL_WRAPPINGS[ sampler.wrapS ] || THREE.RepeatWrapping;
            texture.wrapT = WEBGL_WRAPPINGS[ sampler.wrapT ] || THREE.RepeatWrapping;
            
            return texture;
            
        } );
        
    };
    
    /**
     * Asynchronously assigns a texture to the given material parameters.
     * @param {Object} materialParams
     * @param {string} textureName
     * @param {number} textureIndex
     * @return {Promise}
     */
    GLTFParser.prototype.assignTexture = function ( materialParams, textureName, textureIndex ) {
        
        return this.getDependency( 'texture', textureIndex ).then( function ( texture ) {
            
            materialParams[ textureName ] = texture;
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
     * @param {number} materialIndex
     * @return {Promise<THREE.Material>}
     */
    GLTFParser.prototype.loadMaterial = function ( materialIndex ) {
        
        var parser = this;
        var json = this.json;
        var extensions = this.extensions;
        var materialDef = json.materials[ materialIndex ];
        
        var materialType;
        var materialParams = {};
        var materialExtensions = materialDef.extensions || {};
        
        var pending = [];
        
        if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ] ) {
            
            var sgExtension = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ];
            materialType = sgExtension.getMaterialType( materialDef );
            pending.push( sgExtension.extendParams( materialParams, materialDef, parser ) );
            
        } else if ( materialExtensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ] ) {
            
            var kmuExtension = extensions[ EXTENSIONS.KHR_MATERIALS_UNLIT ];
            materialType = kmuExtension.getMaterialType( materialDef );
            pending.push( kmuExtension.extendParams( materialParams, materialDef, parser ) );
            
        } else {
            
            // Specification:
            // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material
            
            materialType = THREE.MeshStandardMaterial;
            
            var metallicRoughness = materialDef.pbrMetallicRoughness || {};
            
            materialParams.color = new THREE.Color( 1.0, 1.0, 1.0 );
            materialParams.opacity = 1.0;
            
            if ( Array.isArray( metallicRoughness.baseColorFactor ) ) {
                
                var array = metallicRoughness.baseColorFactor;
                
                materialParams.color.fromArray( array );
                materialParams.opacity = array[ 3 ];
                
            }
            
            if ( metallicRoughness.baseColorTexture !== undefined ) {
                
                pending.push( parser.assignTexture( materialParams, 'map', metallicRoughness.baseColorTexture.index ) );
                
            }
            
            materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
            materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;
            
            if ( metallicRoughness.metallicRoughnessTexture !== undefined ) {
                
                var textureIndex = metallicRoughness.metallicRoughnessTexture.index;
                pending.push( parser.assignTexture( materialParams, 'metalnessMap', textureIndex ) );
                pending.push( parser.assignTexture( materialParams, 'roughnessMap', textureIndex ) );
                
            }
            
        }
        
        if ( materialDef.doubleSided === true ) {
            
            materialParams.side = THREE.DoubleSide;
            
        }
        
        var alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;
        
        if ( alphaMode === ALPHA_MODES.BLEND ) {
            
            materialParams.transparent = true;
            
        } else {
            
            materialParams.transparent = false;
            
            if ( alphaMode === ALPHA_MODES.MASK ) {
                
                materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;
                
            }
            
        }
        
        if ( materialDef.normalTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {
            
            pending.push( parser.assignTexture( materialParams, 'normalMap', materialDef.normalTexture.index ) );
            
            materialParams.normalScale = new THREE.Vector2( 1, 1 );
            
            if ( materialDef.normalTexture.scale !== undefined ) {
                
                materialParams.normalScale.set( materialDef.normalTexture.scale, materialDef.normalTexture.scale );
                
            }
            
        }
        
        if ( materialDef.occlusionTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {
            
            pending.push( parser.assignTexture( materialParams, 'aoMap', materialDef.occlusionTexture.index ) );
            
            if ( materialDef.occlusionTexture.strength !== undefined ) {
                
                materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;
                
            }
            
        }
        
        if ( materialDef.emissiveFactor !== undefined && materialType !== THREE.MeshBasicMaterial ) {
            
            materialParams.emissive = new THREE.Color().fromArray( materialDef.emissiveFactor );
            
        }
        
        if ( materialDef.emissiveTexture !== undefined && materialType !== THREE.MeshBasicMaterial ) {
            
            pending.push( parser.assignTexture( materialParams, 'emissiveMap', materialDef.emissiveTexture.index ) );
            
        }
        
        return Promise.all( pending ).then( function () {
            
            var material;
            
            if ( materialType === THREE.ShaderMaterial ) {
                
                material = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ].createMaterial( materialParams );
                
            } else {
                
                material = new materialType( materialParams );
                
            }
            
            if ( materialDef.name !== undefined ) material.name = materialDef.name;
            
            // Normal map textures use OpenGL conventions:
            // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#materialnormaltexture
            if ( material.normalScale ) {
                
                material.normalScale.y = - material.normalScale.y;
                
            }
            
            // baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.
            if ( material.map ) material.map.encoding = THREE.sRGBEncoding;
            if ( material.emissiveMap ) material.emissiveMap.encoding = THREE.sRGBEncoding;
            if ( material.specularMap ) material.specularMap.encoding = THREE.sRGBEncoding;
            
            assignExtrasToUserData( material, materialDef );
            
            if ( materialDef.extensions ) addUnknownExtensionsToUserData( extensions, material, materialDef );
            
            return material;
            
        } );
        
    };
    
    /**
     * @param  {THREE.BufferGeometry} geometry
     * @param  {GLTF.Primitive} primitiveDef
     * @param  {Array<THREE.BufferAttribute>} accessors
     */
    function addPrimitiveAttributes( geometry, primitiveDef, accessors ) {
        
        var attributes = primitiveDef.attributes;
        
        for ( var gltfAttributeName in attributes ) {
            
            var threeAttributeName = ATTRIBUTES[ gltfAttributeName ];
            var bufferAttribute = accessors[ attributes[ gltfAttributeName ] ];
            
            // Skip attributes already provided by e.g. Draco extension.
            if ( ! threeAttributeName ) continue;
            if ( threeAttributeName in geometry.attributes ) continue;
            
            geometry.addAttribute( threeAttributeName, bufferAttribute );
            
        }
        
        if ( primitiveDef.indices !== undefined && ! geometry.index ) {
            
            geometry.setIndex( accessors[ primitiveDef.indices ] );
            
        }
        
        if ( primitiveDef.targets !== undefined ) {
            
            addMorphTargets( geometry, primitiveDef.targets, accessors );
            
        }
        
        assignExtrasToUserData( geometry, primitiveDef );
        
    }
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
     *
     * Creates BufferGeometries from primitives.
     * If we can build a single BufferGeometry with .groups from multiple primitives, returns one BufferGeometry.
     * Otherwise, returns BufferGeometries without .groups as many as primitives.
     *
     * @param {Array<Object>} primitives
     * @return {Promise<Array<THREE.BufferGeometry>>}
     */
    GLTFParser.prototype.loadGeometries = function ( primitives ) {
        
        var parser = this;
        var extensions = this.extensions;
        var cache = this.primitiveCache;
        
        var isMultiPass = isMultiPassGeometry( primitives );
        var originalPrimitives;
        
        if ( isMultiPass ) {
            
            originalPrimitives = primitives; // save original primitives and use later
            
            // We build a single BufferGeometry with .groups from multiple primitives
            // because all primitives share the same attributes/morph/mode and have indices.
            
            primitives = [ primitives[ 0 ] ];
            
            // Sets .groups and combined indices to a geometry later in this method.
            
        }
        
        return this.getDependencies( 'accessor' ).then( function ( accessors ) {
            
            var pending = [];
            
            for ( var i = 0, il = primitives.length; i < il; i ++ ) {
                
                var primitive = primitives[ i ];
                
                // See if we've already created this geometry
                var cached = getCachedGeometry( cache, primitive );
                
                if ( cached ) {
                    
                    // Use the cached geometry if it exists
                    pending.push( cached );
                    
                } else if ( primitive.extensions && primitive.extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ] ) {
                    
                    // Use DRACO geometry if available
                    var geometryPromise = extensions[ EXTENSIONS.KHR_DRACO_MESH_COMPRESSION ]
                        .decodePrimitive( primitive, parser )
                        .then( function ( geometry ) {
                            
                            addPrimitiveAttributes( geometry, primitive, accessors );
                            
                            return geometry;
                            
                        } );
                    
                    cache.push( { primitive: primitive, promise: geometryPromise } );
                    
                    pending.push( geometryPromise );
                    
                } else {
                    
                    // Otherwise create a new geometry
                    var geometry = new THREE.BufferGeometry();
                    
                    addPrimitiveAttributes( geometry, primitive, accessors );
                    
                    var geometryPromise = Promise.resolve( geometry );
                    
                    // Cache this geometry
                    cache.push( { primitive: primitive, promise: geometryPromise } );
                    
                    pending.push( geometryPromise );
                    
                }
                
            }
            
            return Promise.all( pending ).then( function ( geometries ) {
                
                if ( isMultiPass ) {
                    
                    var baseGeometry = geometries[ 0 ];
                    
                    // See if we've already created this combined geometry
                    var cache = parser.multiPassGeometryCache;
                    var cached = getCachedMultiPassGeometry( cache, baseGeometry, originalPrimitives );
                    
                    if ( cached !== null ) return [ cached.geometry ];
                    
                    // Cloning geometry because of index override.
                    // Attributes can be reused so cloning by myself here.
                    var geometry = new THREE.BufferGeometry();
                    
                    geometry.name = baseGeometry.name;
                    geometry.userData = baseGeometry.userData;
                    
                    for ( var key in baseGeometry.attributes ) geometry.addAttribute( key, baseGeometry.attributes[ key ] );
                    for ( var key in baseGeometry.morphAttributes ) geometry.morphAttributes[ key ] = baseGeometry.morphAttributes[ key ];
                    
                    var indices = [];
                    var offset = 0;
                    
                    for ( var i = 0, il = originalPrimitives.length; i < il; i ++ ) {
                        
                        var accessor = accessors[ originalPrimitives[ i ].indices ];
                        
                        for ( var j = 0, jl = accessor.count; j < jl; j ++ ) indices.push( accessor.array[ j ] );
                        
                        geometry.addGroup( offset, accessor.count, i );
                        
                        offset += accessor.count;
                        
                    }
                    
                    geometry.setIndex( indices );
                    
                    cache.push( { geometry: geometry, baseGeometry: baseGeometry, primitives: originalPrimitives } );
                    
                    return [ geometry ];
                    
                } else if ( geometries.length > 1 && THREE.BufferGeometryUtils !== undefined ) {
                    
                    // Tries to merge geometries with BufferGeometryUtils if possible
                    
                    for ( var i = 1, il = primitives.length; i < il; i ++ ) {
                        
                        // can't merge if draw mode is different
                        if ( primitives[ 0 ].mode !== primitives[ i ].mode ) return geometries;
                        
                    }
                    
                    // See if we've already created this combined geometry
                    var cache = parser.multiplePrimitivesCache;
                    var cached = getCachedCombinedGeometry( cache, geometries );
                    
                    if ( cached ) {
                        
                        if ( cached.geometry !== null ) return [ cached.geometry ];
                        
                    } else {
                        
                        var geometry = THREE.BufferGeometryUtils.mergeBufferGeometries( geometries, true );
                        
                        cache.push( { geometry: geometry, baseGeometries: geometries } );
                        
                        if ( geometry !== null ) return [ geometry ];
                        
                    }
                    
                }
                
                return geometries;
                
            } );
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
     * @param {number} meshIndex
     * @return {Promise<THREE.Group|THREE.Mesh|THREE.SkinnedMesh>}
     */
    GLTFParser.prototype.loadMesh = function ( meshIndex ) {
        
        var scope = this;
        var json = this.json;
        var extensions = this.extensions;
        
        var meshDef = json.meshes[ meshIndex ];
        
        return this.getMultiDependencies( [
            
            'accessor',
            'material'
        
        ] ).then( function ( dependencies ) {
            
            var primitives = meshDef.primitives;
            var originalMaterials = [];
            
            for ( var i = 0, il = primitives.length; i < il; i ++ ) {
                
                originalMaterials[ i ] = primitives[ i ].material === undefined
                    ? createDefaultMaterial()
                    : dependencies.materials[ primitives[ i ].material ];
                
            }
            
            return scope.loadGeometries( primitives ).then( function ( geometries ) {
                
                var isMultiMaterial = geometries.length === 1 && geometries[ 0 ].groups.length > 0;
                
                var meshes = [];
                
                for ( var i = 0, il = geometries.length; i < il; i ++ ) {
                    
                    var geometry = geometries[ i ];
                    var primitive = primitives[ i ];
                    
                    // 1. create Mesh
                    
                    var mesh;
                    
                    var material = isMultiMaterial ? originalMaterials : originalMaterials[ i ];
                    
                    if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
                        primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
                        primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
                        primitive.mode === undefined ) {
                        
                        // .isSkinnedMesh isn't in glTF spec. See .markDefs()
                        mesh = meshDef.isSkinnedMesh === true
                            ? new THREE.SkinnedMesh( geometry, material )
                            : new THREE.Mesh( geometry, material );
                        
                        if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ) {
                            
                            mesh.drawMode = THREE.TriangleStripDrawMode;
                            
                        } else if ( primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ) {
                            
                            mesh.drawMode = THREE.TriangleFanDrawMode;
                            
                        }
                        
                    } else if ( primitive.mode === WEBGL_CONSTANTS.LINES ) {
                        
                        mesh = new THREE.LineSegments( geometry, material );
                        
                    } else if ( primitive.mode === WEBGL_CONSTANTS.LINE_STRIP ) {
                        
                        mesh = new THREE.Line( geometry, material );
                        
                    } else if ( primitive.mode === WEBGL_CONSTANTS.LINE_LOOP ) {
                        
                        mesh = new THREE.LineLoop( geometry, material );
                        
                    } else if ( primitive.mode === WEBGL_CONSTANTS.POINTS ) {
                        
                        mesh = new THREE.Points( geometry, material );
                        
                    } else {
                        
                        throw new Error( 'THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode );
                        
                    }
                    
                    if ( Object.keys( mesh.geometry.morphAttributes ).length > 0 ) {
                        
                        updateMorphTargets( mesh, meshDef );
                        
                    }
                    
                    mesh.name = meshDef.name || ( 'mesh_' + meshIndex );
                    
                    if ( geometries.length > 1 ) mesh.name += '_' + i;
                    
                    assignExtrasToUserData( mesh, meshDef );
                    
                    meshes.push( mesh );
                    
                    // 2. update Material depending on Mesh and BufferGeometry
                    
                    var materials = isMultiMaterial ? mesh.material : [ mesh.material ];
                    
                    var useVertexColors = geometry.attributes.color !== undefined;
                    var useFlatShading = geometry.attributes.normal === undefined;
                    var useSkinning = mesh.isSkinnedMesh === true;
                    var useMorphTargets = Object.keys( geometry.morphAttributes ).length > 0;
                    var useMorphNormals = useMorphTargets && geometry.morphAttributes.normal !== undefined;
                    
                    for ( var j = 0, jl = materials.length; j < jl; j ++ ) {
                        
                        var material = materials[ j ];
                        
                        if ( mesh.isPoints ) {
                            
                            var cacheKey = 'PointsMaterial:' + material.uuid;
                            
                            var pointsMaterial = scope.cache.get( cacheKey );
                            
                            if ( ! pointsMaterial ) {
                                
                                pointsMaterial = new THREE.PointsMaterial();
                                THREE.Material.prototype.copy.call( pointsMaterial, material );
                                pointsMaterial.color.copy( material.color );
                                pointsMaterial.map = material.map;
                                pointsMaterial.lights = false; // PointsMaterial doesn't support lights yet
                                
                                scope.cache.add( cacheKey, pointsMaterial );
                                
                            }
                            
                            material = pointsMaterial;
                            
                        } else if ( mesh.isLine ) {
                            
                            var cacheKey = 'LineBasicMaterial:' + material.uuid;
                            
                            var lineMaterial = scope.cache.get( cacheKey );
                            
                            if ( ! lineMaterial ) {
                                
                                lineMaterial = new THREE.LineBasicMaterial();
                                THREE.Material.prototype.copy.call( lineMaterial, material );
                                lineMaterial.color.copy( material.color );
                                lineMaterial.lights = false; // LineBasicMaterial doesn't support lights yet
                                
                                scope.cache.add( cacheKey, lineMaterial );
                                
                            }
                            
                            material = lineMaterial;
                            
                        }
                        
                        // Clone the material if it will be modified
                        if ( useVertexColors || useFlatShading || useSkinning || useMorphTargets ) {
                            
                            var cacheKey = 'ClonedMaterial:' + material.uuid + ':';
                            
                            if ( material.isGLTFSpecularGlossinessMaterial ) cacheKey += 'specular-glossiness:';
                            if ( useSkinning ) cacheKey += 'skinning:';
                            if ( useVertexColors ) cacheKey += 'vertex-colors:';
                            if ( useFlatShading ) cacheKey += 'flat-shading:';
                            if ( useMorphTargets ) cacheKey += 'morph-targets:';
                            if ( useMorphNormals ) cacheKey += 'morph-normals:';
                            
                            var cachedMaterial = scope.cache.get( cacheKey );
                            
                            if ( ! cachedMaterial ) {
                                
                                cachedMaterial = material.isGLTFSpecularGlossinessMaterial
                                    ? extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ].cloneMaterial( material )
                                    : material.clone();
                                
                                if ( useSkinning ) cachedMaterial.skinning = true;
                                if ( useVertexColors ) cachedMaterial.vertexColors = THREE.VertexColors;
                                if ( useFlatShading ) cachedMaterial.flatShading = true;
                                if ( useMorphTargets ) cachedMaterial.morphTargets = true;
                                if ( useMorphNormals ) cachedMaterial.morphNormals = true;
                                
                                scope.cache.add( cacheKey, cachedMaterial );
                                
                            }
                            
                            material = cachedMaterial;
                            
                        }
                        
                        materials[ j ] = material;
                        
                        // workarounds for mesh and geometry
                        
                        if ( material.aoMap && geometry.attributes.uv2 === undefined && geometry.attributes.uv !== undefined ) {
                            
                            console.log( 'THREE.GLTFLoader: Duplicating UVs to support aoMap.' );
                            geometry.addAttribute( 'uv2', new THREE.BufferAttribute( geometry.attributes.uv.array, 2 ) );
                            
                        }
                        
                        if ( material.isGLTFSpecularGlossinessMaterial ) {
                            
                            // for GLTFSpecularGlossinessMaterial(ShaderMaterial) uniforms runtime update
                            mesh.onBeforeRender = extensions[ EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS ].refreshUniforms;
                            
                        }
                        
                    }
                    
                    mesh.material = isMultiMaterial ? materials : materials[ 0 ];
                    
                }
                
                if ( meshes.length === 1 ) {
                    
                    return meshes[ 0 ];
                    
                }
                
                var group = new THREE.Group();
                
                for ( var i = 0, il = meshes.length; i < il; i ++ ) {
                    
                    group.add( meshes[ i ] );
                    
                }
                
                return group;
                
            } );
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
     * @param {number} cameraIndex
     * @return {Promise<THREE.Camera>}
     */
    GLTFParser.prototype.loadCamera = function ( cameraIndex ) {
        
        var camera;
        var cameraDef = this.json.cameras[ cameraIndex ];
        var params = cameraDef[ cameraDef.type ];
        
        if ( ! params ) {
            
            console.warn( 'THREE.GLTFLoader: Missing camera parameters.' );
            return;
            
        }
        
        if ( cameraDef.type === 'perspective' ) {
            
            camera = new THREE.PerspectiveCamera( THREE.Math.radToDeg( params.yfov ), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6 );
            
        } else if ( cameraDef.type === 'orthographic' ) {
            
            camera = new THREE.OrthographicCamera( params.xmag / - 2, params.xmag / 2, params.ymag / 2, params.ymag / - 2, params.znear, params.zfar );
            
        }
        
        if ( cameraDef.name !== undefined ) camera.name = cameraDef.name;
        
        assignExtrasToUserData( camera, cameraDef );
        
        return Promise.resolve( camera );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
     * @param {number} skinIndex
     * @return {Promise<Object>}
     */
    GLTFParser.prototype.loadSkin = function ( skinIndex ) {
        
        var skinDef = this.json.skins[ skinIndex ];
        
        var skinEntry = { joints: skinDef.joints };
        
        if ( skinDef.inverseBindMatrices === undefined ) {
            
            return Promise.resolve( skinEntry );
            
        }
        
        return this.getDependency( 'accessor', skinDef.inverseBindMatrices ).then( function ( accessor ) {
            
            skinEntry.inverseBindMatrices = accessor;
            
            return skinEntry;
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
     * @param {number} animationIndex
     * @return {Promise<THREE.AnimationClip>}
     */
    GLTFParser.prototype.loadAnimation = function ( animationIndex ) {
        
        var json = this.json;
        
        var animationDef = json.animations[ animationIndex ];
        
        return this.getMultiDependencies( [
            
            'accessor',
            'node'
        
        ] ).then( function ( dependencies ) {
            
            var tracks = [];
            
            for ( var i = 0, il = animationDef.channels.length; i < il; i ++ ) {
                
                var channel = animationDef.channels[ i ];
                var sampler = animationDef.samplers[ channel.sampler ];
                
                if ( sampler ) {
                    
                    var target = channel.target;
                    var name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.
                    var input = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.input ] : sampler.input;
                    var output = animationDef.parameters !== undefined ? animationDef.parameters[ sampler.output ] : sampler.output;
                    
                    var inputAccessor = dependencies.accessors[ input ];
                    var outputAccessor = dependencies.accessors[ output ];
                    
                    var node = dependencies.nodes[ name ];
                    
                    if ( node ) {
                        
                        node.updateMatrix();
                        node.matrixAutoUpdate = true;
                        
                        var TypedKeyframeTrack;
                        
                        switch ( PATH_PROPERTIES[ target.path ] ) {
                            
                            case PATH_PROPERTIES.weights:
                                
                                TypedKeyframeTrack = THREE.NumberKeyframeTrack;
                                break;
                            
                            case PATH_PROPERTIES.rotation:
                                
                                TypedKeyframeTrack = THREE.QuaternionKeyframeTrack;
                                break;
                            
                            case PATH_PROPERTIES.position:
                            case PATH_PROPERTIES.scale:
                            default:
                                
                                TypedKeyframeTrack = THREE.VectorKeyframeTrack;
                                break;
                            
                        }
                        
                        var targetName = node.name ? node.name : node.uuid;
                        
                        var interpolation = sampler.interpolation !== undefined ? INTERPOLATION[ sampler.interpolation ] : THREE.InterpolateLinear;
                        
                        var targetNames = [];
                        
                        if ( PATH_PROPERTIES[ target.path ] === PATH_PROPERTIES.weights ) {
                            
                            // node can be THREE.Group here but
                            // PATH_PROPERTIES.weights(morphTargetInfluences) should be
                            // the property of a mesh object under group.
                            
                            node.traverse( function ( object ) {
                                
                                if ( object.isMesh === true && object.morphTargetInfluences ) {
                                    
                                    targetNames.push( object.name ? object.name : object.uuid );
                                    
                                }
                                
                            } );
                            
                        } else {
                            
                            targetNames.push( targetName );
                            
                        }
                        
                        // KeyframeTrack.optimize() will modify given 'times' and 'values'
                        // buffers before creating a truncated copy to keep. Because buffers may
                        // be reused by other tracks, make copies here.
                        for ( var j = 0, jl = targetNames.length; j < jl; j ++ ) {
                            
                            var track = new TypedKeyframeTrack(
                                targetNames[ j ] + '.' + PATH_PROPERTIES[ target.path ],
                                THREE.AnimationUtils.arraySlice( inputAccessor.array, 0 ),
                                THREE.AnimationUtils.arraySlice( outputAccessor.array, 0 ),
                                interpolation
                            );
                            
                            // Here is the trick to enable custom interpolation.
                            // Overrides .createInterpolant in a factory method which creates custom interpolation.
                            if ( sampler.interpolation === 'CUBICSPLINE' ) {
                                
                                track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline( result ) {
                                    
                                    // A CUBICSPLINE keyframe in glTF has three output values for each input value,
                                    // representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
                                    // must be divided by three to get the interpolant's sampleSize argument.
                                    
                                    return new GLTFCubicSplineInterpolant( this.times, this.values, this.getValueSize() / 3, result );
                                    
                                };
                                
                                // Workaround, provide an alternate way to know if the interpolant type is cubis spline to track.
                                // track.getInterpolation() doesn't return valid value for custom interpolant.
                                track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;
                                
                            }
                            
                            tracks.push( track );
                            
                        }
                        
                    }
                    
                }
                
            }
            
            var name = animationDef.name !== undefined ? animationDef.name : 'animation_' + animationIndex;
            
            return new THREE.AnimationClip( name, undefined, tracks );
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
     * @param {number} nodeIndex
     * @return {Promise<THREE.Object3D>}
     */
    GLTFParser.prototype.loadNode = function ( nodeIndex ) {
        
        var json = this.json;
        var extensions = this.extensions;
        
        var meshReferences = json.meshReferences;
        var meshUses = json.meshUses;
        
        var nodeDef = json.nodes[ nodeIndex ];
        
        return this.getMultiDependencies( [
            
            'mesh',
            'skin',
            'camera',
            'light'
        
        ] ).then( function ( dependencies ) {
            
            var node;
            
            // .isBone isn't in glTF spec. See .markDefs
            if ( nodeDef.isBone === true ) {
                
                node = new THREE.Bone();
                
            } else if ( nodeDef.mesh !== undefined ) {
                
                var mesh = dependencies.meshes[ nodeDef.mesh ];
                
                if ( meshReferences[ nodeDef.mesh ] > 1 ) {
                    
                    var instanceNum = meshUses[ nodeDef.mesh ] ++;
                    
                    node = mesh.clone();
                    node.name += '_instance_' + instanceNum;
                    
                    // onBeforeRender copy for Specular-Glossiness
                    node.onBeforeRender = mesh.onBeforeRender;
                    
                    for ( var i = 0, il = node.children.length; i < il; i ++ ) {
                        
                        node.children[ i ].name += '_instance_' + instanceNum;
                        node.children[ i ].onBeforeRender = mesh.children[ i ].onBeforeRender;
                        
                    }
                    
                } else {
                    
                    node = mesh;
                    
                }
                
            } else if ( nodeDef.camera !== undefined ) {
                
                node = dependencies.cameras[ nodeDef.camera ];
                
            } else if ( nodeDef.extensions
                && nodeDef.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ]
                && nodeDef.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ].light !== undefined ) {
                
                var lights = extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ].lights;
                node = lights[ nodeDef.extensions[ EXTENSIONS.KHR_LIGHTS_PUNCTUAL ].light ];
                
            } else {
                
                node = new THREE.Object3D();
                
            }
            
            if ( nodeDef.name !== undefined ) {
                
                node.name = THREE.PropertyBinding.sanitizeNodeName( nodeDef.name );
                
            }
            
            assignExtrasToUserData( node, nodeDef );
            
            if ( nodeDef.extensions ) addUnknownExtensionsToUserData( extensions, node, nodeDef );
            
            if ( nodeDef.matrix !== undefined ) {
                
                var matrix = new THREE.Matrix4();
                matrix.fromArray( nodeDef.matrix );
                node.applyMatrix( matrix );
                
            } else {
                
                if ( nodeDef.translation !== undefined ) {
                    
                    node.position.fromArray( nodeDef.translation );
                    
                }
                
                if ( nodeDef.rotation !== undefined ) {
                    
                    node.quaternion.fromArray( nodeDef.rotation );
                    
                }
                
                if ( nodeDef.scale !== undefined ) {
                    
                    node.scale.fromArray( nodeDef.scale );
                    
                }
                
            }
            
            return node;
            
        } );
        
    };
    
    /**
     * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
     * @param {number} sceneIndex
     * @return {Promise<THREE.Scene>}
     */
    GLTFParser.prototype.loadScene = function () {
        
        // scene node hierachy builder
        
        function buildNodeHierachy( nodeId, parentObject, json, allNodes, skins ) {
            
            var node = allNodes[ nodeId ];
            var nodeDef = json.nodes[ nodeId ];
            
            // build skeleton here as well
            
            if ( nodeDef.skin !== undefined ) {
                
                var meshes = node.isGroup === true ? node.children : [ node ];
                
                for ( var i = 0, il = meshes.length; i < il; i ++ ) {
                    
                    var mesh = meshes[ i ];
                    var skinEntry = skins[ nodeDef.skin ];
                    
                    var bones = [];
                    var boneInverses = [];
                    
                    for ( var j = 0, jl = skinEntry.joints.length; j < jl; j ++ ) {
                        
                        var jointId = skinEntry.joints[ j ];
                        var jointNode = allNodes[ jointId ];
                        
                        if ( jointNode ) {
                            
                            bones.push( jointNode );
                            
                            var mat = new THREE.Matrix4();
                            
                            if ( skinEntry.inverseBindMatrices !== undefined ) {
                                
                                mat.fromArray( skinEntry.inverseBindMatrices.array, j * 16 );
                                
                            }
                            
                            boneInverses.push( mat );
                            
                        } else {
                            
                            console.warn( 'THREE.GLTFLoader: Joint "%s" could not be found.', jointId );
                            
                        }
                        
                    }
                    
                    mesh.bind( new THREE.Skeleton( bones, boneInverses ), mesh.matrixWorld );
                    
                }
                
            }
            
            // build node hierachy
            
            parentObject.add( node );
            
            if ( nodeDef.children ) {
                
                var children = nodeDef.children;
                
                for ( var i = 0, il = children.length; i < il; i ++ ) {
                    
                    var child = children[ i ];
                    buildNodeHierachy( child, node, json, allNodes, skins );
                    
                }
                
            }
            
        }
        
        return function loadScene( sceneIndex ) {
            
            var json = this.json;
            var extensions = this.extensions;
            var sceneDef = this.json.scenes[ sceneIndex ];
            
            return this.getMultiDependencies( [
                
                'node',
                'skin'
            
            ] ).then( function ( dependencies ) {
                
                var scene = new THREE.Scene();
                if ( sceneDef.name !== undefined ) scene.name = sceneDef.name;
                
                assignExtrasToUserData( scene, sceneDef );
                
                if ( sceneDef.extensions ) addUnknownExtensionsToUserData( extensions, scene, sceneDef );
                
                var nodeIds = sceneDef.nodes || [];
                
                for ( var i = 0, il = nodeIds.length; i < il; i ++ ) {
                    
                    buildNodeHierachy( nodeIds[ i ], scene, json, dependencies.nodes, dependencies.skins );
                    
                }
                
                return scene;
                
            } );
            
        };
        
    }();
    
    return GLTFLoader;
    
} )();
